Each of the images is either no longer in copyright or otherwise in the public domain. According to the New York Public Library, no permission is required and there are no restrictions on use.

Blossom Restaurant, Manhattan by Berenice Abbott/The Miriam and Ira D. Wallach Division of Art, Prints and Photographs: Photography Collection, The New York Public Library

They include Depression-era images from photographs like Walker Evans and Dorothea Lange, Lewis Hines' photographic documentation of Ellis Island immigrants, letters written by Alexander Hamilton, Thomas Jefferson, James Madison and political figures, and more.

The future of digitisation

Interestingly, the institution is also providing developer access to the metadata of its collections, and making updates to its API to encourage playful games and visualisations. Why not make a GIF from the vast collection of stereoscopic images?

One image from a series of Egyptian gods and goddesses depicted by a French artist in the early 1800s

NYPL's in-house technology department has also released a number of interactive "public domain releases". One such remix is Navigating the Green Book, which assembles road-trip itineraries from addresses listed in mid-20th-century travel guides for African Americans.

Enter in your start and end points, reports CityLab, and the tool will spit out restaurants, hotels, gas stations, and sights that didn't discriminate against blacks in an age of sundown towns and segregation.

The free images made avaliable by the New York Public Library are fascinating. But be warned: once you start browsing, you'll lose the rest of your day.